1. Field of the Invention
The present invention relates to a scroll type compressor for compressing refrigerant gas, and, more specifically, relates to a scroll type compressor that is suitable for use in an air conditioner for vehicles and is capable of being driven at a high efficiency and a low load.
2. Description of Prior Art
A scroll type compressor being driven at a low load is disclosed, for example, in JP-A-10-115292. The main portion of this scroll type compressor is depicted in FIG. 6. In FIG. 6, fixed scroll member 11xe2x80x2 and orbital scroll member 12xe2x80x2 are assembled within housing 20xe2x80x2 to define compression pocket 15xe2x80x2 for compressing refrigerant gas. Fixed scroll member 11xe2x80x2 has a first spiral element 11axe2x80x2 provided on a first end plate 11bxe2x80x2, and orbital scroll member 12xe2x80x2 has a second spiral element 12axe2x80x2 provided on a second end plate 12bxe2x80x2. First and second spiral elements 11axe2x80x2 and 12axe2x80x2 have substantially the same axial height and have spiral patterns that are different from each other. Fixed scroll member 11xe2x80x2 and orbital scroll member 12xe2x80x2 are assembled so that the first and second spiral elements interfit at an angular and radial offset to form a plurality of line contacts that define at least one pair of sealed off compression pockets. As compression pocket 15xe2x80x2 moves inwardly, the refrigerant gas therein is compressed.
In the compressor, an open portion 16 is provided on fixed scroll member 11xe2x80x2 at a position corresponding to an intermediate compression stage position of compression pocket 15xe2x80x2. A hole 20axe2x80x2 is defined on housing 20xe2x80x2 at a position facing open portion 16. A pipe member 13 having a gas discharging path 17 therein and having a screw portion thereon is inserted into hole 20axe2x80x2. Pipe member 13 is fixed to fixed scroll member 11xe2x80x2 and housing 20xe2x80x2 and sealed via seal rings 14a and 14b, such that gas discharging path 17 communicates open portion 16 and extends therefrom to the outside of the compressor. Seal rings 14a and 14b operate to prevent gas leakage when pipe member 13 is attached to fixed scroll member 11xe2x80x2 and housing 20xe2x80x2.
In such a compressor, an opening/closing device (not shown) is provided in gas discharging path 17 of pipe member 13. The opening/closing device opens gas discharging path 17 to discharge gas from discharging path 17 to the outside of the compressor, for example, to the low pressure side of an external refrigerant circuit, when the load of the compressor is not higher than a predetermined value. Such a mechanism may enable a high-efficiency and low-load operation of the compressor. In a scroll type compressor, because a pair of compression pockets having the same compression stage are defined, the above-described mechanism is provided generally by two sets of gas discharge mechanisms.
In such a conventional mechanism for a scroll type compressor, however, two sets of gas discharging mechanisms are provided, and each mechanism includes pipe member 13 having gas discharging path 17, seal rings 14a and 14b and fixing and sealing structure therefor. In the mechanism, the number of parts may be great. Further, because the position of pipe member 13 depends on the position of fixed scroll member 11xe2x80x2 assembled in housing 20xe2x80x2, it is difficult to ensure its positional accuracy. Further, if seal rings 14a and 14b are improperly disposed into fixed scroll member 11xe2x80x2 and housing 20xe2x80x2, they may be deformed or cut, and a rattling may occur. To prevent such an inconvenience, seal rings 14a and 14b must be assembled very carefully, and skillfully.
Accordingly, it is an object of the present invention to provide an improved structure for a scroll type compressor that may decrease the number of parts, may have a good assembling ability, and may operate at a high efficiency and a low load.
To achieve the foregoing and other objects, a scroll type compressor according to the present invention is herein provided. The scroll type compressor includes a fixed scroll member and an orbital scroll member disposed within a housing for defining a compression pocket for compressing refrigerant gas, an open portion provided on the fixed scroll member at a position corresponding to an intermediate compression stage position of the compression pocket, and a mechanism for discharging refrigerant gas intermediately compressed in the compression pocket out of the compressor through the open portion. The refrigerant gas discharging mechanism comprises a gas discharging path formed in the housing itself to communicate the open portion.
In the scroll type compressor, a first space portion may be formed on the open portion of the fixed scroll member, and the first space portion communicates the gas discharging path of the housing. Alternatively, a second space portion may be formed on the gas discharging path of the housing, and the second space portion communicates the open portion of the fixed scroll member. Still alternatively, a third space portion may be formed on a contact portion of the fixed scroll member and the housing, and the third space portion communicates the open portion of the fixed scroll member and the gas discharging path of the housing.
Further, in the scroll type compressor, a pair of compression pockets each having an identical compression stage may be defined by the fixed scroll member and the orbital scroll member. The open portion may be provided at each position corresponding to an intermediate compression stage position of each compression pocket, and both open portions communicate each other via the first, second or third space portion described above.
The gas discharging path may be formed to extend in a direction across an axis of a shaft provided in the compressor for driving the orbital scroll member. In the scroll type compressor, a throttling mechanism may be further provided for adjusting an amount of refrigerant gas discharged from the gas discharging path. The refrigerant gas discharged and adjusted in amount may be sent to a gas introduction path connected to an inlet port of the compressor and introduced with a low pressure refrigerant gas.
In the scroll type compressor according to the present invention, the gas discharging path is formed in the housing itself instead of a conventional pipe member having a gas discharging path which is attached to a fixed scroll member and a housing via seal rings. Therefore, the number of parts for forming a gas discharging path may be greatly reduced. Moreover, because the gas discharging path is formed in the housing itself and another particular member is not necessary for forming the gas discharging path, the structure may be formed small and simple. When the gas discharging path is formed to extend in a direction across an axis of the shaft for driving the orbital scroll member, particularly the axial size of the compressor may be further decreased. In addition because the gas discharging path is defined in the housing without positioning a certain member, the gas discharging path may be easily formed at a proper and desired position with a high accuracy, thereby improving the assembling ease.
Further, when the first, second or third space portion is formed between the fixed scroll member and the housing, the respective compressed gas discharged through a pair of compression pockets may easily join via the space portion. The joined gas may be smoothly discharged through the gas discharging path. Consequently, an excellent scroll type compressor capable of operating at a high efficiency and a low load may be achieved.
Further, when the throttling mechanism for adjusting the amount of the discharged refrigerant gas is provided, the gas adjusted in amount may be sent to a gas introduction circuit with a low pressure. The amount of gas may be controlled depending the requirements, thereby achieving a more efficient operation of the compressor at a lower load.
Further objects, features, and advantages of the present invention will be understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying figures.